Pre-notification with rfid dock door portals

ABSTRACT

Embodiments presented herein describe an RFID system for detecting RFID tags in order to track inventory such as a pallet or individual packages. The RFID system includes at least one portal located in an inventory transport area. For example, the portal may be disposed at or near a dock door in a warehouse in order to detect when an RFID tag (and the corresponding inventory) passes through the door—e.g., when the inventory is loaded onto a truck. In one embodiment, the portal defines at least two RFID detection regions. For example, the portal may generate a RFID sensing region and a RFID read region. In one embodiment, a wide beam antenna generates the RFID sensing region while a narrow beam antenna generates the RFID read region.

BACKGROUND

Shipping warehouses can use radio frequency identification (RFID)systems to track inventory. RFID tags, which can be passive or active,are disposed on the inventory (e.g., individual boxes or pallets) in thewarehouse and are programmed with information identifying the associatedinventory. The identifying information is read from the RFID tags byRFID readers. In one example, the RFID readers are located at loadingdocks or loading bays so that an inventory tracking system can detectwhen RFID tags (and the corresponding inventory) pass through a dockdoor when being loaded into, or offloaded from, a truck. In this manner,the inventory tracking system can determine what inventory is in thewarehouse.

In one example, the inventory tracking system uses the RFID system toensure the inventory passes through the correct loading dock, and thus,is loaded onto the correct truck. That is, the inventory tracking systemassigns an RFID tag (or tags) to a particular dock door and uses theRFID readers to ensure the RFID tag (and the corresponding inventory)pass through the correct dock door. If, however, the inventory trackingsystem determines that an RFID tag passes through an incorrect dockdoor, the tracking system can alert a warehouse worker who can removethe inventory from the truck and transport the inventory to the correctloading dock. However, current RFID systems can take several seconds toalert the warehouse worker or the truck driver that an RFID tag haspassed through an incorrect dock door. By that time, the worker may havealready dropped off the inventory in the truck and returned to thewarehouse. After receiving the alert, the worker has to return to thetruck and find the inventory. Providing alerts earlier can reduce thetime required to correct mistakes when loading inventory.

BRIEF DESCRIPTION OF DRAWINGS

Various embodiments in accordance with the present disclosure will bedescribed with reference to the drawings, where like designations denotelike elements.

FIG. 1 illustrates an RFID system for tracking RFID tags in a warehouse,according to various embodiments.

FIG. 2 illustrates a top view of RFID read and sensing regions generatedby the portals, according to various embodiments.

FIG. 3 illustrates a front surface of a portal, according to variousembodiments.

FIGS. 4A and 4B illustrate top views of the portals, according tovarious embodiments.

FIG. 5 is a block diagram of an RFID system which includes portals fortracking RFID tags, according to various embodiments.

FIG. 6 is a flowchart for operating the portals, according to variousembodiments.

FIG. 7 is a flowchart for determining whether an RFID tag has moved inthe RFID read or sensing regions, according to various embodiments.

DETAILED DESCRIPTION

Embodiments presented herein describe an RFID system for detecting RFIDtags in order to track inventory such as a pallet or individualpackages. The RFID system includes at least one portal located in aninventory transport area. For example, the portal may be disposed at ornear a dock door in a warehouse in order to detect when an RFID tag (andthe corresponding inventory) passes through the door—e.g., when theinventory is loaded onto a truck. In one embodiment, the portal definesat least two RFID detection regions. For example, the portal maygenerate a RFID sensing region and a RFID read region. In oneembodiment, a wide beam antenna generates the RFID sensing region whilea narrow beam antenna generates the RFID read region.

The antennas can be arranged in the portal such that the RFID sensingregion (i.e., the radiation pattern of the wide beam antenna) covers aregion of the loading dock that extends further away from the dock doorand the portal than the RFID read region (i.e., the radiation pattern ofthe narrow beam antenna). As such, in one embodiment, the RFID systemuses the RFID sensing region as an early detection sensing region todetect when an RFID tag is in the loading dock and is approaching thedock door. The RFID system can use the narrower RFID read region todetermine when the RFID tag has passed by the portal and through thedock door and is being loaded into the truck. In this way, the RFIDsensing region provides preliminary feedback regarding whether the RFIDtagged inventory is at the correct loading dock, and can also activatethe RFID read region in anticipation of the inventory entering the RFIDread region. Such a multi-regional sensing portal allows earlieractivation of the RFID read region than is possible using sensing meanssuch as a laser sensor provisioned in the RFID read region or otherconventional means.

FIG. 1 illustrates an RFID system 100 for tracking RFID tags in awarehouse 105, according to various embodiments. As shown, the warehouse105 includes multiple dock doors 115 which permit a warehouse worker (oran autonomous vehicle) to load inventory into, or retrieve inventoryfrom, a truck 110. In FIG. 1, the dock door 115A is open while the dockdoors 115B and 115C are closed. As such, the dock door 115A provides aview into the warehouse 105 and a loading dock. In this embodiment, theloading dock includes two portals 120A-B (generally referred to hereinas portals 120) which are disposed at or near opposite sides of the dockdoor 115A. The portals 120 can be disposed in any manner to ensure thatinventory passing through the dock door 115A also pass between theportals 120.

In FIG. 1, each of the portals 120 include at least one RFID reader andantenna (not shown) which establish a RFID read region 125. That is, therespective radiation patterns of the antennas in the portals can becombined to form the RFID read region 125. When an RFID tag moves withinthe RFID read region 125, the tag detects the radio waves emitted by theantennas in the portals 120 and transmits a modulated RFID response thatincludes identification (ID) data corresponding to the tag. In oneembodiment, each RFID tag is assigned a unique ID which the RFID system100 uses to track to the tags. This allows inventory to be tracked atthe individual unit level. In other embodiments, inventory is tracked atthe type or category level. For example, the RFID tags may be given IDswhich are generic to a specific type or category of inventory—e.g., allRFID tags attached to packages containing hair dryers have a firstshared ID while all RFID tags attached to packages containing curlingirons have a second shared ID which is different than the first sharedID.

The RFID readers in the portals 120 receive the modulated RFID responsesfrom the tags and demodulate the data in the responses to identify theID for the tag. The portal can report the tag ID to an inventorytracking system which determines whether the RFID tag is assigned to thedock door 115A. In one embodiment, the inventory tracking systemincludes a tag database which assigns the RFID tags to a particular dockdoor 115 which each can have a corresponding RFID scanning system thatincludes at least one portal 120. For example, a fulfillment system maypopulate the entries in the tag database in response to a customerplacing an order for inventory stored in the warehouse 105. Thefulfillment system can select inventory in the warehouse 105 to satisfythe customer order, identify the RFID tag (or tags) corresponding to theselected inventory, and assign the RFID tag to a particular dock door115 using the tag database so that the inventory is loaded into a truckwhich is assigned to the geographic region of the customer.

A warehouse worker can receive instructions from the fulfillment systemto retrieve the inventory and load the inventory into a truck at thecorresponding dock door. However, multiple errors can result in thewrong inventory being loaded into the truck. For example, the wrong RFIDtag could have been placed on the inventory, the worker may retrieve thewrong inventory, or the worker may move the inventory to the wrong dockdoor. Using the portals 120 and the associated RFID read region 125, theinventory tracking system can detect when a mistake has been made anduse indicators 130 to inform the warehouse worker that there is aproblem.

In FIG. 1, the indicators 130 are lights mounted on the top of theportal 120B. For example, the indicators 130 may include a red light forindicating when there is in an error and a green light for indicatingthat the RFID tag is at the correct dock door. However, the indicators130 can include any number of lights for indicating any number ofdifferent of scenarios—e.g., a third light indicating when the RFIDreader cannot accurately determine the ID for the RFID tag. In otherembodiments, the indicators 130 can be mounted on both portals 130 oroutside of the warehouse 105 (such that they are viewable to the truckdriver). Moreover, the indicators 130 can output audio alerts inaddition to (or as an alternative to) visual alerts. In anotherembodiment, the inventory tracking system can send alerts electronicallyto a mobile phone or tablet carried by the warehouse worker or a qualitycontrol specialist, or directly to an autonomous vehicle moving theinventory.

If the RFID tag read by the portal 120 is intended to be delivered tothe dock door 115A, the inventory tracking system may illuminate a greenlight of the indicators 130 indicating to the worker to proceed withloading the inventory into the truck. However, if the RFID tag is notintended for the dock door 115A, the inventory tracking systemilluminates a red light indicating to the worker there is an error.

If an error is detected, the worker may move the inventory from theloading dock to a staging area or a designated location. A qualitycontrol specialist may be tasked with identifying the correct dock door115 for the inventory. For example, the specialist may use a predefinedworkflow process to troubleshoot the problem and identify the solution,such as placing the correct RFID tag on the inventory, restocking theincorrect inventory and retrieving the correct inventory, or moving theinventory to the appropriate loading dock.

FIG. 2 illustrates a top view of the RFID read and sensing regionsgenerated by the portals, according to various embodiments. This topview includes a dock edge 205 which illustrates where a truck can backup to in order to load and unload inventory from the warehouse and astaging area boundary 235 where pallets 220 can be stored when waitingto be loaded into the truck. The area between the dock edge 205 and thestaging area boundary 235, and between the portal 120A and the portal120B is referred to herein as the loading dock or loading bay.

Each of the portals 120 include a narrow beam antenna for generating arespective narrow radiation pattern 210 (shown using solid lines) and awide beam antenna for generating a respective wide radiation pattern 215(shown using dotted lines). That is, the narrow beam antenna in theportal 120A emits the narrow radiation pattern 210A while the wide beamantenna in the portal 120A emits the wide radiation pattern 215A.Similarly, the narrow beam antenna in the portal 120B emits the narrowradiation pattern 210B while the wide beam antenna in the portal 120Bemits the wide radiation pattern 215B. The combined area covered by thenarrow radiation patterns 210A and 210B is defined as the read region125 while the combined area covered by the wide radiation patterns 215Aand 210B is defined as the sensing region 240.

In this embodiment, the read region 125 extends primarily between theportal 120A and 120B. However, the portals 120 can control the size anddirection of the narrow radiation patterns 210 to adjust the locationand size of the read region 125 as desired. For example, by controllingthe beam width of the narrow beam antennas, the emission power of theantennas, and the facing direction of the antennas, the portals 120 canchange the size and location of the read region 125. In FIG. 2, thenarrow radiation patterns 210 are set so that read region 125 primarilyincludes the area directly in front of the dock edge and between theportals 120. A system designer can control the narrow radiation patterns210 to limit the read region 125 from extending in the area between theportals 120 and the staging area boundary 235 (although it may extendinto this region some as shown in FIG. 2). As a result, if only the readregion 125 is active (i.e., the wide beam antennas are turned off), theRFID tag 270A on pallet 220A would not be detected by the RFID readersin the portals 120. That is, because the RFID tag 270A is not in theread region 125, the tag 270A is not detected by the portals 120(although changes in the physical environment in the warehouse may causethe read region 125 to change such that the RFID tag 270A isoccasionally detected by the RFID readers in the portals 120 albeit witha low signal strength).

The wide radiation patterns 215 in FIG. 2 are set such that the sensingregion 240 generally covers the area of the loading dock that is betweenthe portals 120 and the staging area boundary 235. As such, when thewide beam antennas are active, the RFID readers in the portals 120 candetect when an RFID tag passes over the staging area boundary 235 intothe loading dock and begins to move towards the dock edge 205. Thus, theportals 120 report the tag 270A (and the pallet 220A) as being locatedwithin the sensing region 240 to the inventory tracking system 250 whichis communicatively coupled to one or both of the portals 120. Putdifferently, the portals 120 can inform the inventory tracking system250 that the pallet 220A has moved into the loading dock.

Although FIG. 2 illustrates that the wide radiation patterns 215 and thesensing region 240 are contained within the loading dock—i.e., does notextend into the staging area or to the left of the portal 120B or theright of the portal 120A—this is an idealized illustration. In practice,the sensing region 240 may extend into the staging area or intoneighboring loading docks. Moreover, the sensing region 240 may changeas the physical objects in the environment move around which can resultin tags 270 that were once outside of the sensing region 240 to bedetected. However, as described below, the portals 120 can account forthe dynamic nature of the read region 125 and the sensing region 240 byusing power thresholds and monitoring the signals received from the RFIDtags 270 over time. For example, the tags 270B, 270C, and 270D on thepallets 220B, 220C, and 220D in the staging area may occasionally bedetected by the RFID reader but the portal 120 may ignore their signalsbecause the signals are below an RSSI threshold.

In FIG. 2, a pallet mover 330 moves the pallet 220A from the stagingarea into the loading dock. Eventually, the pallet mover 330 moves thepallet 220A over the dock edge 205 and into the truck. As describedbelow, the portals 120 use the read region 125 and the sensing region240 to ensure that the pallet 220A is within the loading dock and thatthe loading dock is assigned to the RFID tag 270A. If not, the portals120 can use indicators to alert a worker that the pallet 220A should notbe loaded onto the truck.

Although FIG. 2 illustrates using two portals 120, in one embodiment,the RFID system 100 can include only one portal 120 per loading dock(e.g., one portal disposed at each dock door). However, having twoportals 120 (or more than two portals 120) can increase the accuracy ofthe RFID system 100 and enable better control of the sizes and locationsof the read and sensing regions 125 and 240. Moreover, instead of usingseparate antennas to generate the narrow radiation pattern 210 and thewide radiation pattern 215, the portals 120 can use one antenna togenerate the two radiation patterns, according to other embodiments. Forexample, the portal 120 can control a power setting of the antenna anduse beam forming to generate the two different size radiation patternsshown in FIG. 2 with one stationary antenna. In another embodiment, theportal 120 can include one or more actuators to change the orientationof the antenna (as well as adjust the gain of the antenna) to generatethe narrow and wide radiation patterns 210 and 215.

In one non-limiting example, the portals 120 are spaced 10 feet apart(+/−2 feet) and are spaced within two feet from the dock edge 205 (orfrom an external wall of the warehouse). Further, dock edge 205 may be13.5 feet (+/−2 feet) from the staging area boundary 235. The widths (W)of the read region 125 and the sensing region 240 (i.e., the directionbetween the portals 120) is approximately 10 feet. The length (L) of theread region 125 at its longest point may be approximately 6.5 feet. Thelength of the sensing region 240 at its longest point may beapproximately 11 feet.

FIG. 3 illustrates a front surface 300 of the portal 120A, according tovarious embodiments. Referring to FIG. 2, in one embodiment, the frontsurface 300 is the side of the portal 120A that is facing the portal120B. In this example, the front surface 300 includes two narrow beamantennas 305 and two wide beam antennas 310. As mentioned above, inother embodiments, the portal 120A can include only one narrow beamantenna 305 and only one wide beam antenna 310. Further, the portal 120Acan include three, four, or more of the narrow and wide beam antennas305 and 310.

The optimal distance between the pairs of antennas can vary depending onthe specific antennas used. For example, a center-to-center distance 315between the narrow beam antennas 305 and a center-to-center distance 320between the wide beam antennas 310 can change depending on the beamwidth or aperture of the antennas. As the beam width or aperturenarrows, the distances 315 and 320 may be reduced. Conversely, if thebeam width or aperture of the antennas widens, the distances 315 and 320are spaced farther apart. In one embodiment, the beam widths of thenarrow and wide beam antennas 305 and 310 and the distances 315 and 320can be set such that the RFID tags can be detected with an accuracy ofgreater than 99% when in the read region.

In one embodiment, the portal 120A has a width in the horizontaldirection of approximately 20 inches, a height in the vertical directionof approximately 6 feet, and a depth in a direction into the page ofapproximately 10 inches.

In one embodiment, the antennas in the front surface of the portal 120Bcan have the same arrangement as the front surface 300 shown here. Thatis, the center-to-center distances for the pairs of antennas can be thesame in both portals 120.

FIGS. 4A and 4B illustrate top views of the portals 120, according tovarious embodiments. In FIG. 4A, the narrow band antennas 305 and thewide band antennas 310 in each of the portals 120 are arranged at anangle relative to a reference axis 400 (shown by the vertical dottedlines) that is perpendicular to the dock edge 205. Specifically, thenarrow beam antennas 305 are offset by an angle θ_(N) from the axis 400while the wide beam antennas are offset an angle θ_(W) from the axis400. In one embodiment, the offset angle θ_(N) ranges from 0 degrees to20 degrees while the offset angle θ_(W) ranges from 35 degrees to 55degrees. As mentioned above, the particular value of the angles θ_(N)and θ_(W) can vary depending on the desired size and location of theread and sensing regions generated by the portals 120.

Although FIG. 4A illustrates only one of the narrow and wide beamantennas 305 and 310 in each of the portals, the other narrow and widebeam antennas 305 and 310 in the portals 120 can have the samearrangement relative to the axis 400. For example, the narrow beamantenna 305B in the portal 120A can have the same offset angle θ_(N)relative to the axis 400, while the wide beam antenna 310B has the sameoffset angle θ_(W) relative to the axis 400.

In FIG. 4A, the narrow beam antennas 305 are disposed closer to the dockdoor 205 than the wide beam antennas 310. However, in FIG. 4B, the widebeam antennas 310 are disposed closer to the dock door 205. Although twoarrangements of antennas are shown, the antennas 305 and 310 can bedisposed in any manner to provide read and the sensing regions foridentifying RFID tags as described herein.

FIG. 5 is a block diagram of the RFID system 100 which includes theportal 120 for tracking RFID tags 270, according to various embodiments.In addition to the portal 120 and the RFID tag 270, the RFID system 100also includes the inventory tracking system 250, a dock door sensor 535,and a motion sensor 540 which are all communicatively coupled to theportal 120.

In the illustrative embodiment, the portal 120 includes a narrow beamantenna 305 a wide beam antenna 310, an RFID reader 520, the indicators130, a communication module 525, and a portal controller 530. Althoughthe portal 120 illustrates one narrow and wide beam antenna 310, theportal 120 may include multiple antennas. For example, using two, three,four, etc. of each of the antennas can improve spatial diversity andaccuracy when detecting the RFID tags 270.

When energized, the narrow beam antenna 305 establishes the RFID readregion 120 while the wide beam antenna 310 establishes a RFID sensingregion 240. The different characteristics of the RFID read region 120and the RFID sensing region 240 are illustrated in FIG. 2 which resultfrom the different beams or apertures of the narrow and wide beamantennas 305 and 310 as well as the arrangement of the antennas 305 and310 within the portal 120 as shown in FIGS. 3 and 4. In one embodiment,the RFID sensing region 240 is used as an early detection region foridentifying the RFID tag 270 in the loading dock before the tag 270 haspassed by the portal 120 or the through the dock door. For example, theRFID sensing region 240 can cover a region of the loading dock whichextends away from the dock door and towards an internal portion of thewarehouse (e.g., a staging area in the warehouse). The RFID read region125, in contrast, may primarily include a region between two portals 120flanking the dock door. In one embodiment, the sensing region 240 coversa larger area than the read region 125.

In addition to transmitting RFID signals to the RFID tag 270, the narrowbeam antenna 305 and the wide beam antenna 310 receive RFID signals fromthe tag 270. The received RFID signals (or responses) are read by theRFID reader 520. In one embodiment, the RFID reader 520 includes ademodulator for identifying an ID 580 of the RFID tag 270. In thismanner, the reader 520 can identify tags that enter into the RFID readregion 125 and the RFID sensing region 240. Moreover, the RFID reader520 can generate metrics regarding the received RFID responses such asthe signal strength of the RFID signals (e.g., received signal strengthindicator (RSSI)).

The communication module 525 communicatively couples the portal 120 tothe inventory tracking system 250, the dock door sensor 535, and themotion sensor 540. In one embodiment, the communication module 525 is anetwork adapter that communicates with the inventory tracking system 250using a local area network (LAN) or wide access network (WAN). Moreover,the communication module 525 can use wired or wireless means in order tocommunicate with external systems and devices.

The portal controller 530 may include one or more processors orprocessing elements that control the operation of the portal 120 asdescribed herein. Moreover, the portal controller 530 can includefirmware and/or software applications. In one embodiment, the portalcontroller 530 can receive the tag ID 580 and the signal strengthcorresponding to the ID 580 from the RFID reader 520 and determine alocation of the tag 270 in one of the regions 125 and 240. In addition,the portal controller 530 can receive signals from the dock door sensor535 and dock motion sensor 540 to determine whether the dock door isopen or closed and whether a worker or vehicle is moving in the loadingdock. The portal controller 530 can transmit information such as thelocation of the RFID tag 270 to the inventory tracking system 250 usingthe communication module 525.

The inventory tracking system 250 includes a portal communication module555 and a tag tracker 560. The portal communication module 555 can be anetwork adapter for communicating with the portal 120 using a LAN orWAN. The tag tracker 560 uses the information about the location of theRFID tag 270 provided by the portal controller 530 to update a tagdatabase 565. In one embodiment, the tag database 565 maps the ID 580 ofthe tag 270 to a particular location in the warehouse—e.g., whether thetag is in the RFID read region 125, the RFID sensing region 240, or onthe truck. In some embodiments, the tag database 565 may also track thetag 270 at other locations in the warehouse such as in the staging areaor on a shelf. In any case, the portal controller 530 can use theinformation provided by the RFID reader 520 to identify a location ofthe RFID tag 270 which is then communicated to the tag tracker 560 whichupdates the tag database 565. The tag tracker 560 can include hardwareelements, software elements, or some combination of both.

The inventory tracking system 250 can be a computing system disposed inthe warehouse or external to the warehouse. For example, the inventorytracking system 250 can be an application executing in a data center ora cloud computer environment which is communicatively coupled to theportal 120 via the Internet.

The RFID tag 270 can be a passive or active tag. If passive, the RFIDtag 270 uses the RFID signals emitted by the narrow beam antenna 305 andthe wide beam antenna 310 to power its internal components (e.g., themodulator 575) in order to transmit a RFID response back to the portal120 which includes the ID 580 encoded therein. Put differently, apassive RFID tag 270 does not need an internal battery but is insteaduses the incident RFID signals to transmit a response that includes itsID 580. An active RFID tag, in contrast, includes a power supply whichcan be used to operate its internal components such as a receiver or themodulator 575. Although passive RFID tags are typically less expensive,active RFID tags can be sensed at greater ranges. In one embodiment, theactive RFID tags transmit their corresponding ID after receiving theRFID signals transmitted by the antennas in the portal 120. However, inanother embodiment, the active RFID tags function as beacons where thetags constantly transmit their IDs. In this example, the antennas in theportal do not need to emit the RFID signals but can be used to sense theRFID signals emitted by the active RFID tag.

FIG. 6 is a flowchart of a method 600 for operating portals at a loadingdock, according to various embodiments. The method 600 begins at block605 where the portal controller determines whether the dock door isopen. In one embodiment, the portal controller is communicativelycoupled to the dock door sensor which outputs a signal indicatingwhether the door is open or closed.

Once the dock door is opened, the method 600 proceeds to block 610 wherethe portal controller determines if there is movement in the loadingdock. Here, the portal controller receives an input from the dock motionsensor which can be mounted above the dock door. In one embodiment, thedock motion sensor is a RF sensor that uses a frequency band that isoutside of the frequency band (or bands) used by RFID sensing. Forexample, the dock motion sensor may use 24.150 GHz Doppler radar inorder to determine if there is motion in the loading dock. Using thedock motion sensor, the portal controller can wait until a worker or anautonomous vehicle moves into the vicinity of the loading dock beforeactivating the RFID read or sensing regions. Doing so may save power aswell as prevent the portals from transmitting RFID signal when there isno movement in the loading dock which can interfere with sensing regionsgenerated by portals in neighboring loading docks and cause falsepositives (e.g., indicate a pallet is moving when the pallet is in factstationary).

In one embodiment, however, block 610 may be omitted from the method600. For example, the RFID system may not include the motion sensor, andthus, method 600 may skip block 610 and proceed directly to block 615.At block 615, the portal controller activates the sensing region usingthe wide beam antenna in the portal. In one embodiment, the loading dockincludes at least two portals, in which case the portal controller mayactivate the wide beam antennas on both of the portals in parallel suchthat their combined radiation patterns form the sensing region.

As shown in FIG. 2, the radiation patterns can be controlled such thatthe sensing region covers the area of the loading dock that is betweenthe portals (which may be disposed at or near—e.g., within two feet fromthe dock edge) and the staging area. Although the dock motion sensor caninform the portal controller when there is movement in the loading dock,the sensing region can inform the portal controller whether the movementis attributable to inventory being moved from the staging area towardsthe dock edge. Put differently, because the sensing region isestablished by transmitting RFID signals, the RFID tags on the inventorycan transmit their IDs to the portals which can be used to track theinventory. In this manner, the portal controller can identify whatinventory is currently in the loading dock.

In one embodiment, the sensing region formed by the wide band antennasin the portal (or multiple portals) is an early detection sensing regionthat identifies inventory that is approaching the portals. As such, thesensing region may cover a path used by a pallet mover when loadinginventory into a truck using the loading dock.

At block 620, the portal controller (or the inventory tracking system)determines whether an RFID tag moves into the sensing region. Thedetails of block 620 are described in more detail in FIG. 7, butgenerally the portal controller can monitor the signal strength (e.g.,RSSI) of the RFID response transmitted by the RFID tag when in thesensing region over time to determine whether the RFID tag is moving.For example, the physical environment in the warehouse can cause thesignal strength of the RFID response to change even if the tag issitting stationary. Thus, in one embodiment, the portal controller canmonitor the signal strength over time and use thresholds to detect whenthe inventory is moving versus when the inventory is stationary.

If no RFID tags are moving, the method 600 returns to block 610 to waitfor motion sensor to again detect motion in the loading dock. Forexample, the previously detected movement could have been caused by aworker walking between loading docks (without moving inventory). If theRFID system does not have a dock motion sensor, the method 600 couldstay at block 620 where the portal controller continues to monitor RFIDtags using the sensing region to determine if one of the tags changeslocations. However, if the portal controller does determine at block 620that the RFID tag moved into the sensing region, the method 600 proceedsto block 625 where the portal controller activates the read region usingthe narrow beam antennas.

In one embodiment, when activating the read region, the portalcontroller deactivates the sensing region. Put differently, the portalcontroller stops the wide band antennas from transmitting RFID signalswhen the narrow band antennas begin transmitting the RFID signalsestablishing the read region. Doing so may help the portal controllerensure that the RFID tag has moved from the sensing region into the readregion. If the sensing region is deactivated, the portal controller canknow that any received RFID responses from the tag were generatedbecause the tag moved into the read region. Stated differently, the tagtransmits RFID signals in response to the RFID signals emitted by thenarrow beam antennas, and not in response to the RFID signals emitted bythe wide beam antennas. However, even if the wide beam antennas are notused to transmit the RFID signals when the read region is active, thewide beam antennas can still be used to receive the RFID response fromthe tag. In another embodiment, however, the narrow and wide beamantennas can both be transmitting RFID signals (e.g., both the sensingregion and the read region are active at the same time) and the portalcontroller can use the signal strength of the RFID response transmittedby the tag to determine if the tag is in the read region or is in thesensing region.

As illustrated in FIG. 2, the read region 125 can be generated toprimarily cover the area between the portals 120. Because in oneembodiment the read region 125 is activated after the RFID tag 270A isdetected in the sensing region 240, the read region 125 can be activatedbefore the tag 270A has moved into the read region 125—e.g., when thetag 270A is still only in the sensing region 240. Nonetheless, becausethe read region 125 is active, the portals 120 can detect the RFID tag270A as soon as the tag 270A enters the read region 125. In comparison,in another embodiment, the portals 120 may include laser sensors thatdirect light between the portals 120. Instead of activating the readregion 125 in response to detecting the tag 270A in the sensing region240, the portals 120 wait until the pallet 220A breaks the beam of thelaser sensors to activate the read region 125. However, at this point,the RFID tag 270A may have already entered the area covered by the readregion 125, and thus, could have been detected sooner if the read region125 was active. Thus, using the sensing region 240 to activate the readregion 125 may reduce the time used by the portals 120 to providefeedback indicating to the warehouse worker whether the pallet 220A isassigned to the current loading dock.

In another embodiment, to increase the ability to provide the feedbacksooner, the laser sensors could be disposed in the area between theportals 120 and the staging area boundary 235 (e.g., halfway between theportals 120 and the boundary 235). However, the laser sensors do nothave the ability to determine whether the object that breaks its beam isinventory or a worker walking through the loading dock without movinginventory. Thus, the read region 125 could be activated when there is noRFID tagged inventory in the loading dock. Further, disposing the lasersensors in the loading dock (external to the portals) can be a hazardwhich can trip a warehouse worker or impede an autonomous mover frommoving freely within the loading dock. Thus, one advantage of using thesensing region 240 is that the wide beam antennas can be disposed in theportals 120, which means RFID tagged inventory can be detected withoutplacing additional structures in the loading dock.

At block 630, the portal controller determines whether the RFID tagmoves into the read region. Like block 620, the details of block 630 aredescribed in more detail in FIG. 7, but generally the portal controllercan monitor the signal strength (e.g., RSSI) of the RFID responsetransmitted by the RFID tag over time to determine whether the RFID tagis moving in the read region. If the RFID tag is not moving through theread region (e.g., the tag is not currently passing through the readregion to be loaded onto the truck), the method 600 returns to block 610to wait for additional movement in the loading dock. If the RFID systemdoes not have a dock motion sensor, the method 600 could instead returnto block 615.

If movement within the read region is detected, the method 600 proceedsto block 635 where the portal controller reports to the inventorytracking system that the inventory marked with the RFID tag is in theread region and is about to be loaded into the truck. In response, theinventory tracking system can determine whether the RFID tag and theinventory have been assigned to that loading dock or truck. In oneembodiment, the inventory tracking system includes the tag database 565illustrated in FIG. 5 which assigns the RFID tags to a particularloading dock or truck. Once the portal controller determines the RFIDtag is in the read region, the inventory tracking system can query thetag database to determine if the tag is assigned to that loading dock.

At block 640, the portal controller provides audio or visual feedbackdepending on whether the inventory tracking system determines if theRFID tag is assigned to the loading dock. If the tag is assigned to theloading dock, the portal controller can activate the appropriateindicator (e.g., a green light on the portal or an audio sound). If not,the portal controller can illuminate a red light or send an electronicmessage to a supervisor or the truck driver. In one embodiment, theportal controller may indicate that there is an error if the RFID tagdetected using the sensing region at block 620 is not the same RFID tagdetected using the read region at block 630. That is, if the same tagpassing the read region was not detected in the sensing region, theportal controller may illuminate an amber light indicating that therewas an error with the process performed by the RFID system and that thepallet should be removed from the loading dock and returned to thestaging area where the worker can again move the pallet through thesensing and read regions.

In one embodiment, to further increase the responsiveness of the RFIDsystem, the inventory tracking system queries the tag database after thetag is detected in the sensing region at block 620. That is, before theread region is activated, the portal controller can transmit the RFIDtag ID identified in the sensing region to the inventory tracking systemwhich determines if the tag is assigned to that portal by querying thetag database. Thus, once the tag is identified at block 630 (e.g., afterthe RFID system determines the inventory is being loaded onto thetruck), the portal controller already knows whether the tag is intendedfor the truck and can provide the appropriate feedback as discussedabove. In this embodiment, the portal controller does not need to waitfor the inventory tracking system to query the tag database once theRFID tag is detected in the read region. Instead, the portal controlleralready knows whether the RFID tag is intended for the loading dock andcan provide immediate feedback to the worker after ensuring theinventory is moving through the read region and is being loaded onto thetruck.

FIG. 7 is a flowchart of a method 700 for determining whether an RFIDtag has moved into the RFID read or sensing regions, according tovarious embodiments. The method 700 can be performed to detect movementin the sensing region or the read region which corresponds to blocks 620and 630 in the method 600. Put differently, the method 700 describes atechnique for determining whether an RFID tag has moved into the sensingand read regions. Thus, the method 700 can begin after blocks 615 or 625of FIG. 6.

At block 705, the portal controller determines if an RFID tag isdetected. Stated differently, the portal controller determines if it hasreceived an RFID response to the RFID signals transmitted in the sensingor read regions using the wide or narrow beam antennas. In oneembodiment, the portal controller detects an RFID tag when thecontroller can successfully decode the modulated signals received fromthe RFID tag in order to identify the tag ID.

If no tag is detected, the method 700 proceeds to block 610 of FIG. 6.Otherwise, the method 700 proceeds to block 710 where the portalcontroller determines if the RSSI of the received RFID responsesatisfies a first threshold. For example, the portal controller maydetermine if the RSSI of the received signal is above a noise floorrepresented by the first threshold. In one embodiment, the firstthreshold may be set so that RFID tags located outside the loading dockare not identified as being within the loading dock. For example,multiple RFID tags may be placed at the staging area in preparation ofbeing loaded onto the truck. Because the sensing region may extend intoa portion of the staging area, these RFID tags may transmit RFIDresponse which are detected by the portal. However, by setting asufficiently high threshold, the portal controller can ignore theseresponses since the signals are too weak to come from an RFID tag movingin the sensing region.

If the RSSI does not satisfy the first threshold, the method 700proceeds to block 610 of FIG. 6. Otherwise, the method 700 proceeds toblock 720 where the portal controller performs a cross read to identifythe tag in the dock. In this embodiment, it is assumed that one pallet(and one RFID tag) is loaded into the truck at a time. Thus, in thisexample, there should not be multiple RFID tags moving in the sensing orread regions. If only one RFID tag is detected, the method 700 canproceed to block 725 without performing further analysis. However,because there can be multiple loading docks adjacent to each other in awarehouse, the portal may detect tags that are moving in an adjacentdock (e.g., the sensing or read regions may extend into neighboringloading docks). To the perspective of the portal controller, it canappear as if multiple RFID tags are moving towards the same dock door.

The cross read enables the portal controller to determine which one ofthe tags identified at block 710 is in the loading dock. For example,the portal controller may compare results by portal controllers inneighboring loading docks to determine which of the RFID tags theydetect. For example, if a portal in a neighboring loading dock hasdetected only one of the two RFID tags detected at the current loadingdock, the portal controller can determine that the RFID tag detected byboth of the portals is in the neighboring loading dock while the otherRFID tag is in its loading dock.

At block 725, the portal controller determines if the RSSI of the taghas changed over time by a second threshold. Here, the portal controllermonitors the RSSI over a period of time to track the RSSI of the signalsreceived from the RFID tag. As mentioned above, changes in theenvironment surrounding the RFID tag can cause the signal strength todecrease and increase although the RFID tag remains stationary. The RSSIof the signals emitted by the tag may spike or drop suddenly between twosamples even though the RFID tag has not moved. By evaluating thesechanges over time (e.g., taking the average of thousands or millions ofsamples obtained over a 1-5 second period), the portal controller candetermine whether the change in the average RSSI has satisfied thesecond threshold. Stated differently, the portal controller determineswhether the change in RSSI over a predetermined time period issufficient to indicate the RFID tag is moving.

If the change in RSSI does not satisfy the second threshold, the method700 proceeds to block 610 of FIG. 6. Otherwise, the method 700 proceedsto block 730 where the portal controller determines if this is the firsttime the tag has been detected. In one embodiment, block 730 is usedwhen the sensing region is active but may be omitted if the read regionis active. That is, because the tag first passes through the sensingregion before the read region, an unknown tag should first be detectedwhen the sensing region is active. However, also performing block 730when the read region is active can be used as a check to ensure thatmethod 600 was performed properly—i.e., the same RFID tag that wasdetected in the sensing region is then detected in the read region.

If it is the first time the tag tracker or inventory tracking system hasdetected the tag, the method 700 proceeds to block 735 where the tagtracker adds the tag to the tag database. When doing so, at block 730,the tag tracker stores the current location of the tag in the tagdatabase (e.g., the sensing or read region of a particular loadingdock). Thus, in addition to storing a loading dock assignment for thetag, at block 740, the tag database can store the last known location ofthe tag. Moreover, the tag database can store other parameterscorresponding to the RFID tag such as a transition coefficient, averageRSSI, and peak RSSI. For example, the peak RSSI may be compared at block725 to future RSSI measurements to determine whether the RFID tag hastransitioned or moved to a different region in the warehouse.

In one embodiment, the tag database may store tags only for a fixed timeperiod (e.g., 24 hours). Thus, if a tag is not detected within that timeframe, it is removed from the tag database and is again added to thedatabase once the tag is detected by an RFID system. In one embodiment,the tag database may store information about tags in a single warehouse.However, in another embodiment, the tag database can store currentlocation information for tags at multiple warehouses and distributioncenters. In this example, the tag database is a central repository whichtracks tags as the associated inventory moves into different locationsand buildings of a distribution network. For example, after the taggedinventory is shipped, the tag database can be updated after theinventory is unloaded at a different regional warehouse and passesthrough a portal.

If the inventory tracking system indicates the tag has been detectedpreviously at block 730, the method 700 proceeds to block 745 where thetag tracker determines whether the tag has changed locations. In oneembodiment, the tag tracker compares the location of the tag stored inthe tag database with the current location being reported by the portal.For example, if the tag database indicates the RFID tag was previouslydetected at Loading Dock A but is now detected in the sensing region atLoading Dock B, the tag tracker knows the tag has moved. In anotherembodiment, the tag tracker may track a location of the tags that are inthe same loading dock. For example, if the tag database indicates thetag was most recently in the sensing region of Loading Dock A, but nowthe portal indicates the tag is in the read region of Loading Dock A,the tag tracker may determine the tag has moved.

If the tag has moved, the method 700 proceeds to block 750; otherwise,the method 700 returns to block 610 of FIG. 6. At block 750, the tagtracker reports that the tag has moved to a different location from whatwas stored in the tag database. In one embodiment, the tag trackerupdates the tag database to reflect the current location of the RFIDtag.

If the method 700 is performed to detect movement in the sensing region,the method 700 proceeds to block 625 where the read region is activated.If the method 700 is performed to detect movement in the read region,the method 700 proceeds to block 635 where the portal controller reportsthat the RFID tagged inventory is being loaded into the truck.

In the preceding, reference is made to embodiments presented in thisdisclosure. However, the scope of the present disclosure is not limitedto specific described embodiments. Instead, any combination of thedescribed features and elements, whether related to differentembodiments or not, is contemplated to implement and practicecontemplated embodiments. Furthermore, although embodiments disclosedherein may achieve advantages over other possible solutions or over theprior art, whether or not a particular advantage is achieved by a givenembodiment is not limiting of the scope of the present disclosure. Thus,the preceding aspects, features, embodiments and advantages are merelyillustrative and are not considered elements or limitations of theappended claims except where explicitly recited in a claim(s).

As will be appreciated by one skilled in the art, the embodimentsdisclosed herein may be embodied as a system, method or computer programproduct. Accordingly, aspects may take the form of an entirely hardwareembodiment, an entirely software embodiment (including firmware,resident software, micro-code, etc.) or an embodiment combining softwareand hardware aspects that may all generally be referred to herein as a“circuit,” “module” or “system.” Furthermore, aspects may take the formof a computer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may be usedto implement embodiments of the invention. The computer readable mediummay be a computer readable signal medium or a computer readable storagemedium. A computer readable storage medium may be, for example, but notlimited to, an electronic, magnetic, optical, electromagnetic, infrared,or semiconductor system, apparatus, or device, or any suitablecombination of the foregoing. More specific examples (a non-exhaustivelist) of the computer readable storage medium would include thefollowing: an electrical connection having one or more wires, a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), an optical fiber, a portable compact disc read-onlymemory (CD-ROM), an optical storage device, a magnetic storage device,or any suitable combination of the foregoing. In the context of thisdocument, a computer readable storage medium is any tangible medium thatcan contain, or store a program for use by or in connection with aninstruction execution system, apparatus or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Aspects of the present disclosure are described with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodimentspresented in this disclosure. It will be understood that each block ofthe flowchart illustrations and/or block diagrams, and combinations ofblocks in the flowchart illustrations and/or block diagrams, can beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality and operation of possible implementations ofsystems, methods and computer program products according to variousembodiments. In this regard, each block in the flowchart or blockdiagrams may represent a module, segment or portion of code, whichcomprises one or more executable instructions for implementing thespecified logical function(s). It should also be noted that, in somealternative implementations, the functions noted in the block may occurout of the order noted in the figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts, or combinations of special purpose hardware andcomputer instructions.

In view of the foregoing, the scope of the present disclosure isdetermined by the claims that follow.

1. A radio frequency identification (RFID) system, comprising: aninventory tracking system storing a first assignment between a portaland RFID tags, wherein the inventory tracking system comprises a tagdatabase, wherein each entry in the tag database indicates an RFID tagID, a previous location of an RFID tag, and a second assignment of theRFID tag to at least one door in a building; and at least two portalsdisposed opposite one another to form a passageway therebetween, whereinat least one of the portals comprises: a wide beam antenna configured toemit RFID signals to establish a sensing region; a narrow beam antennaconfigured to emit RFID signals to establish a read region; an RFIDreader; and a portal controller configured to: activate the sensingregion; upon detecting the RFID tag in the sensing region using the RFIDreader, activate the read region; upon detecting the RFID tag in theread region using the RFID reader, report to the inventory trackingsystem that the RFID tag is passing through the passageway; and provideat least one of audio and visual feedback after receiving confirmationfrom the inventory tracking system that the RFID tag is assigned to theportal.
 2. (canceled)
 3. The RFID system of claim 1, wherein detectingthat the RFID tag is in the sensing region comprises: comparing acurrent location received from the portal controller to the previouslocation of the RFID tag stored in the tag database; and determiningthat the RFID tag is in the sensing region when the current location isdifferent from the previous location.
 4. The RFID system of claim 1,wherein detecting that the RFID tag is in the sensing region comprises:receiving multiple RFID responses from the RFID tag over a time period;and determining whether a change in a received signal strength indicator(RSSI) value corresponding to the multiple RFID responses has satisfieda threshold indicating the RFID tag has moved.
 5. The RFID system ofclaim 1, wherein the RFID tag is a passive tag, wherein the RFID tagcomprises a modulator configured to use the RFID signals received fromthe portals to transmit a modulated RFID response comprising the RFIDtag ID of the RFID tag.
 6. A portal, comprising: a first antenna; asecond antenna, wherein a beam width of the first antenna is wider thana beam width of the second antenna; an RFID reader; a visual indicator;and a portal controller configured to: activate a sensing region byemitting RFID signals from the first antenna, wherein the sensing regionis activated in response to receiving a signal from a sensor indicatingthat a door at which the portal is located is open; upon detecting anRFID tag is in the sensing region using the RFID reader, activate a readregion by emitting RFID signals from the second antenna; determinewhether the RFID tag is in the read region based on receiving RFIDsignals from the RFID tag; and operate the visual indicator to outputfeedback based on determining whether the RFID tag is assigned to thedoor.
 7. The portal of claim 6, wherein the first antenna is arranged inthe portal to have a first angle of offset relative to a reference axisand the second antenna is arranged in the portal to have a second angleof offset relative to the reference axis, wherein the first angle ofoffset is greater than the second angle of offset.
 8. (canceled)
 9. Theportal of claim 6, wherein the visual indicator is configured to outputa first color light when the RFID tag is assigned to the door and asecond, different color of light when the RFID tag is not assigned tothe door.
 10. (canceled)
 11. The portal of claim 6, further comprising:a third antenna with a same beam width as the first antenna; and afourth antenna with a same beam width as the second antenna, wherein thefirst and third antennas are configured to emit RFID signals in parallelto establish the sensing region and the second and fourth antennas areconfigured to emit RFID signals in parallel to establish the readregion, wherein the sensing region is larger than the read region. 12.The portal of claim 6, wherein detecting the RFID tag is in the sensingregion comprises: determining that a current location of the RFID tag isdifferent from a previously stored location of the RFID tag.
 13. Theportal of claim 6, detecting the RFID tag is in the sensing regioncomprises: determining whether a change in a RSSI value corresponding tosignals received from the RFID tag over a predefined time period satisfya threshold.
 14. A method, comprising: activating a sensing region inresponse to determining that a door at which a portal is located is openby emitting RFID signals from a first antenna disposed in the portal;upon detecting an RFID tag is moving in the sensing region, activating aread region by emitting RFID signals from a second antenna disposed inthe portal, wherein a beam width of the first antenna is wider than abeam width of the second antenna; determining whether the RFID tag is inthe read region based on receiving RFID signals from the RFID tag; andoutputting a visual indicator based on determining whether the RFID tagis assigned to the door.
 15. The method of claim 14, wherein the firstantenna is arranged in the portal to have a first angle of offsetrelative to a reference axis and the second antenna is arranged in theportal to have a second angle of offset relative to the reference axis,wherein the first angle of offset is greater than the second angle ofoffset.
 16. (canceled)
 17. The method of claim 14, wherein outputtingthe visual indicator comprises: outputting a first color light when theRFID tag is assigned to the door; and outputting a second, differentcolor of light when a different RFID tag detected by the portal is notassigned to the door.
 18. (canceled)
 19. The method of claim 14, whereindetecting the RFID tag is moving in the sensing region comprises:determining that a current location of the RFID tag is different from apreviously stored location of the RFID tag.
 20. The method of claim 14,wherein detecting the RFID tag is in the sensing region comprises:determining whether a change in a RSSI value corresponding to signalsreceived from the RFID tag over a predefined time period satisfy athreshold.